[vcf-midatlantic] Drive repairs, was Hard drive art

Jason Perkins perkins.jason at gmail.com
Mon Apr 22 07:52:09 EDT 2019

It uses the optical sensor for formatting, and if I recall correctly for
large head movements. Fine movements are done with servo information on the


On Mon, Apr 22, 2019 at 7:39 AM David Gesswein via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> On Sun, Apr 21, 2019 at 05:04:25PM -0400, Jason Perkins via
> vcf-midatlantic wrote:
> > Some drives (Apple Widget, Plus Hardcard / Quantum) had a fine position
> > sensor on the head arm. The Lisa disk uses this during a low level
> format.
> >
> Found picture of the drives online. Looks like they used an optical
> position
> sensor similar to how my RK05's work. This was probably the last gasp of
> that method before the track density got too high for it to work.
> Are you saying the Widget only uses it to format? How does it determine
> head position during normal operation? For my RK05 its always uses the
> optical sensor for positioning the heads.

Jason Perkins
313 355 0085

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